Persistent pain after breast cancer treatment: a critical review of risk factors and strategies for prevention.

UNLABELLED: Chronic pain after breast cancer treatment is a major clinical problem, affecting 25 to 60% of patients. Development of chronic pain after breast cancer treatment, as well as other surgical procedures, involves a complex pathophysiology that involves pre-, intra- and post-operative factors. This review is a systematic analysis on methodology and evidence in research into persistent pain after breast cancer treatment during the period 1995 to 2010, in order to clarify the significance and relative role of potential risk factors. Literature was identified by a search in PubMed and OVID, as well as by obtaining relevant studies from a systematic review of reference lists. Sixty papers were identified, most of these being retrospective or questionnaires. Only 2 studies included quantitative sensory testing and only 26 studies were prospective. Furthermore, about a third of the studies did not apply modern principles of surgical and adjuvant therapy. In summary, the data show inconsistencies in definition of chronic pain and treatment groups, as well as in the collection of pre- intra- and post-operative data, precluding conclusions with regard to pathophysiologic mechanisms as well as rational strategies for prevention and treatment. However, nerve damage and radiotherapy appear to be significant risk factors for chronic pain. A proposal for the design of future prospective studies is presented. PERSPECTIVE: A comprehensive and systematic approach to research in chronic pain after breast cancer treatment is necessary in order to understand the pathophysiology and thus develop strategies for prevention and treatment.